1. Field of the Invention
This invention relates to an apparatus for entrapping insects relative to population studies for agricultural crops.
2. Description of the Prior Art
Sampling habitats to determine the distribution and abundance of arthropods is a preliminary phase of any basic or applied work on insect-plant interactions. Data collecting for research purposes requires precise estimates of parameter values.
Measurements taken to estimate population density fall into these groups: absolute methods, relative methods, and population indices. Population indices do not count insects at all, but rather they are a measure of insect products or effects.
Absolute methods yield estimates as density per unit of land area in the habitat. Absolute methods provide data of the type most often desired by population ecologists. Successive estimates of the number of insects per unit of land area are necessary for constructing life tables and for nearly all other studies of population dynamics of uncaged field populations. Unfortunately most methods used by entomologists are relative methods which yield density per unit other than land area and cannot be converted to absolute estimates without a major effort to correct for the insect's behavior and/or the effect of habitat. Insect nets and vacuum sweeping devices are examples of relative methods.
For many years researchers have attempted absolute samples by whole plant examinations. Whole-plant examination in the field required no special equipment. The plants within a given area are simply examined in situ. Examination for insects usually started at the lower branches and systematically progressed to the terminal growth at the top. The disadvantages in this technique are many. First many insects escape detection by moving out of the area or hiding. Identification of species is difficult without magnification which is not practical in most field situations. Record keeping is extremely difficult during whole plant examinations and mistakes are impossible to correct.
Gonzales et al. (Journal of Economic Entomology, Vol. 63, No. 5, pp. 1704-1706, 1970) reported on a "clam shell" device for estimating absolute insect populations on cotton. This method solved several problems associated with obtaining absolute samples. It prevented the escape of insects and allowed counting and identification in the laboratory, but this method requires the removal of plants from the study area which is not desirable in most research situations. Another disadvantage of this approach lies largely in the processing of the sample. Arthropods must be separated from the plant material which is very time consuming.
The lack of quantitation of almost all past work involving field populations of beneficial arthropods in cotton renders most of these data unsuitable for use with mathematical computer models used in pest management.